Yes, the module is mostly unmaintained, there have been just a couple of releases since 2005 and also its API is rather limited, hard to use and full of subtle gotchas.

Also, at the time I posted my answer, the state of Net::SSH::Perl (which is used by Net::SFTP under the hood) was quite similar, around 2014 Steffen Schwigon took it over and between him and Lance Kinley, they did and incredible work renovating the module, adding support for modern algorithms (interoperability at that point was quite bad) and in general, just improving it... but then the latest release was in 2017.